diff --git a/astrbot/core/platform/sources/napcat/napcat_platform_adapter.py b/astrbot/core/platform/sources/napcat/napcat_platform_adapter.py
index 322ca1273e..08bda8c609 100644
--- a/astrbot/core/platform/sources/napcat/napcat_platform_adapter.py
+++ b/astrbot/core/platform/sources/napcat/napcat_platform_adapter.py
@@ -4,7 +4,7 @@
 import re
 import uuid
 from collections.abc import Awaitable, Callable, Mapping
-from pathlib import PurePosixPath
+from pathlib import Path, PurePosixPath
 from time import monotonic
 from typing import Any, cast
 
@@ -63,6 +63,11 @@
 from astrbot.core.platform.platform_metadata import PlatformMetadata
 from astrbot.core.platform.register import register_platform_adapter
 from astrbot.core.utils.error_redaction import safe_error
+from astrbot.core.utils.media_utils import (
+    MediaResolver,
+    file_uri_to_path,
+    is_file_uri,
+)
 
 from ..aiocqhttp.forward_node_splitter import split_long_text_node
 from .codec import (
@@ -156,6 +161,65 @@
 
 _EXCLUSIVE_OUTBOUND_SEGMENTS = (Node, Nodes, File, Video, Record)
 _SPLIT_SEND_INTERVAL_SECONDS = 0.5
+_PORTABLE_MEDIA_PREFIXES = ("http://", "https://", "base64://")
+_OutboundMedia = Image | Record | Video | File
+
+
+def _outbound_media_candidates(component: _OutboundMedia) -> list[str]:
+    if isinstance(component, File):
+        values = (component.file_, component.url)
+    else:
+        values = (component.file, component.url, component.path)
+    candidates: list[str] = []
+    for value in values:
+        if value and value not in candidates:
+            candidates.append(value)
+    return candidates
+
+
+def _local_media_ref_exists(value: str) -> bool:
+    try:
+        path = Path(file_uri_to_path(value) if is_file_uri(value) else value)
+        return path.exists()
+    except OSError:
+        return False
+
+
+def _first_prefixed_media_ref(
+    candidates: list[str], prefixes: tuple[str, ...]
+) -> str | None:
+    for value in candidates:
+        if value.startswith(prefixes):
+            return value
+    return None
+
+
+def _first_readable_media_ref(candidates: list[str]) -> str | None:
+    for value in candidates:
+        if value.startswith("data:") or _local_media_ref_exists(value):
+            return value
+    return None
+
+
+def _pass_through_media_fields(
+    component: _OutboundMedia, file_value: str
+) -> dict[str, str | None]:
+    if file_value.startswith("base64://"):
+        return {}
+    extra: dict[str, str | None] = {}
+    url = component.url or None
+    if url and (
+        url.startswith(_PORTABLE_MEDIA_PREFIXES)
+        or url == file_value
+        or (is_file_uri(url) and not _local_media_ref_exists(url))
+    ):
+        extra["url"] = url
+    if isinstance(component, File):
+        return extra
+    path = component.path or None
+    if path and not _local_media_ref_exists(path):
+        extra["path"] = path
+    return extra
 
 
 class NapCatOutboundProtocol:
@@ -1167,6 +1231,35 @@ def _append_basic_outbound_segments(
             return True
         return False
 
+    @staticmethod
+    async def _portable_media_file(component: _OutboundMedia) -> str | None:
+        """Return a OneBot file value NapCat can consume without AstrBot paths."""
+        candidates = _outbound_media_candidates(component)
+        portable = _first_prefixed_media_ref(candidates, _PORTABLE_MEDIA_PREFIXES)
+        if portable:
+            return portable
+        readable = _first_readable_media_ref(candidates)
+        if readable is None:
+            return candidates[0] if candidates else None
+        try:
+            encoded = await MediaResolver(readable, media_type="file").to_base64()
+        except asyncio.CancelledError:
+            raise
+        except Exception as exc:
+            logger.warning(
+                "[NapCat] Failed to encode outbound %s: %s",
+                component.__class__.__name__,
+                safe_error("", exc),
+            )
+            return None
+        if not encoded:
+            logger.warning(
+                "[NapCat] Outbound %s encoding produced an empty payload",
+                component.__class__.__name__,
+            )
+            return None
+        return f"base64://{encoded}"
+
     async def _append_media_outbound_segment(
         self,
         component: BaseMessageComponent,
@@ -1175,54 +1268,50 @@ async def _append_media_outbound_segment(
     ) -> bool:
         """Convert image, audio, video, and file components."""
         if isinstance(component, Image | Record | Video):
-            file_value = component.file or component.url or component.path
+            file_value = await self._portable_media_file(component)
+            if isinstance(component, Image):
+                label = "[Image]"
+            elif isinstance(component, Record):
+                label = "[Record]"
+            else:
+                label = "[Video]"
             if not file_value:
-                return False
+                segments.append(self.client.text(label))
+                fallback_parts.append(label)
+                return True
+            extra = _pass_through_media_fields(component, file_value)
             if isinstance(component, Image):
-                segments.append(
-                    self.client.image(
-                        file=file_value,
-                        url=component.url or None,
-                        path=component.path or None,
-                    )
-                )
-                fallback_parts.append("[Image]")
+                segments.append(self.client.image(file=file_value, **extra))
             elif isinstance(component, Record):
-                segments.append(
-                    self.client.record(
-                        file=file_value,
-                        url=component.url or None,
-                        path=component.path or None,
-                    )
-                )
-                fallback_parts.append("[Record]")
+                segments.append(self.client.record(file=file_value, **extra))
             else:
                 segments.append(
                     self.client.video(
                         file=file_value,
-                        url=component.url or None,
-                        path=component.path or None,
                         thumb=component.cover or None,
+                        **extra,
                     )
                 )
-                fallback_parts.append("[Video]")
+            fallback_parts.append(label)
             return True
 
         if not isinstance(component, File):
             return False
-        file_value = await component.get_file(allow_return_url=True)
+        file_value = await self._portable_media_file(component)
+        label = f"[File:{component.name}]" if component.name else "[File]"
         if not file_value:
-            return False
+            segments.append(self.client.text(label))
+            fallback_parts.append(label)
+            return True
+        extra = _pass_through_media_fields(component, file_value)
         segments.append(
             self.client.file(
                 file=file_value,
-                url=component.url or None,
                 name=component.name or None,
+                **extra,
             )
         )
-        fallback_parts.append(
-            f"[File:{component.name}]" if component.name else "[File]"
-        )
+        fallback_parts.append(label)
         return True
 
     async def _build_outbound_message(
diff --git a/docs/en/dev/plugin-platform-adapter.md b/docs/en/dev/plugin-platform-adapter.md
index 45f87fc2b5..895211bb55 100644
--- a/docs/en/dev/plugin-platform-adapter.md
+++ b/docs/en/dev/plugin-platform-adapter.md
@@ -226,27 +226,27 @@ Adapters return immutable `MessageDeliveryCapabilities` from `message_capabiliti
 
 The following conservative inventory was checked against this checkout's senders under `astrbot/core/platform/sources/` on 2026-09-11. It does not claim live-account testing on every platform:
 
-| Adapter directory         | Deliverable media                         | Main restriction or handling                                                                                   |
-| ------------------------- | ----------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
-| `aiocqhttp`               | Image, audio, video, file                 | OneBot segments; preserve content order and mapped quotes                                                      |
-| `napcat`                  | Image, audio, video, file                 | OneBot/NapCat segments; native content declared by kind                                                        |
-| `telegram`                | Image, audio, video, file                 | Bridge sends parts in order; 4096 text limit; never reuse another Bot's file_id                                |
-| `discord`                 | Image, audio, file                        | 2000 text limit; cross-session forwarding disables mention notifications; video is delivered as a generic file |
-| `kook`                    | Image, audio, video, file                 | Separate component sends; quotes and JSON cards                                                                |
-| `lark`                    | Image, audio, video, file                 | Lark sender handles cards and uploads; bridge quotes use summaries                                             |
-| `line`                    | Image, audio, video, file                 | At most 5 parts per request and 5000 text characters; public HTTPS `callback_api_base`                         |
-| `mattermost`              | Image, audio, video, file                 | Upload media first; quotes use root_id                                                                         |
-| `misskey`                 | Image, audio, video, file                 | Media depends on the upload setting; instance-specific text limit; quote summaries                             |
-| `satori`                  | Image, audio, video, file                 | Acceptance also depends on the Satori backend and connected platform                                           |
-| `slack`                   | Image, file                               | Blocks/uploads; bridge text uses plain_text; quote summaries                                                   |
-| `dingtalk`                | Image, audio, video, file                 | Media-specific uploads and templates; quote summaries                                                          |
-| `qqofficial`              | Image, audio, video, file                 | Runtime name qq_official; checks cached IDs and proactive mode; channel media conservatively limited to images |
-| `qqofficial_webhook`      | Image, audio, video, file                 | Runtime name qq_official_webhook; shares official sending logic and session restrictions                       |
-| `webchat`                 | Image, audio, video, file                 | Delivered through the WebChat queue; bridge quote summaries                                                    |
-| `wecom`                   | Image, audio, video, file                 | Application mode needs agent_id; customer-service mode cannot send proactively                                 |
-| `wecom_ai_bot`            | Image, audio, video, file                 | Proactive sending needs a push Webhook; video uploads as a file                                                |
-| `weixin_oc`               | Image, audio, video, file                 | Depends on the account connection and platform session context                                                 |
-| `weixin_official_account` | Inbound images and audio can be projected | Current send_by_session rejects proactive delivery; usable as a watch source                                   |
+| Adapter directory         | Deliverable media                         | Main restriction or handling                                                                                                                                                       |
+| ------------------------- | ----------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `aiocqhttp`               | Image, audio, video, file                 | OneBot segments; preserve content order and mapped quotes                                                                                                                          |
+| `napcat`                  | Image, audio, video, file                 | OneBot/NapCat segments; AstrBot-readable local/file:// media is encoded as `base64://`; HTTP, existing base64, and NapCat-side paths pass through; native content declared by kind |
+| `telegram`                | Image, audio, video, file                 | Bridge sends parts in order; 4096 text limit; never reuse another Bot's file_id                                                                                                    |
+| `discord`                 | Image, audio, file                        | 2000 text limit; cross-session forwarding disables mention notifications; video is delivered as a generic file                                                                     |
+| `kook`                    | Image, audio, video, file                 | Separate component sends; quotes and JSON cards                                                                                                                                    |
+| `lark`                    | Image, audio, video, file                 | Lark sender handles cards and uploads; bridge quotes use summaries                                                                                                                 |
+| `line`                    | Image, audio, video, file                 | At most 5 parts per request and 5000 text characters; public HTTPS `callback_api_base`                                                                                             |
+| `mattermost`              | Image, audio, video, file                 | Upload media first; quotes use root_id                                                                                                                                             |
+| `misskey`                 | Image, audio, video, file                 | Media depends on the upload setting; instance-specific text limit; quote summaries                                                                                                 |
+| `satori`                  | Image, audio, video, file                 | Acceptance also depends on the Satori backend and connected platform                                                                                                               |
+| `slack`                   | Image, file                               | Blocks/uploads; bridge text uses plain_text; quote summaries                                                                                                                       |
+| `dingtalk`                | Image, audio, video, file                 | Media-specific uploads and templates; quote summaries                                                                                                                              |
+| `qqofficial`              | Image, audio, video, file                 | Runtime name qq_official; checks cached IDs and proactive mode; channel media conservatively limited to images                                                                     |
+| `qqofficial_webhook`      | Image, audio, video, file                 | Runtime name qq_official_webhook; shares official sending logic and session restrictions                                                                                           |
+| `webchat`                 | Image, audio, video, file                 | Delivered through the WebChat queue; bridge quote summaries                                                                                                                        |
+| `wecom`                   | Image, audio, video, file                 | Application mode needs agent_id; customer-service mode cannot send proactively                                                                                                     |
+| `wecom_ai_bot`            | Image, audio, video, file                 | Proactive sending needs a push Webhook; video uploads as a file                                                                                                                    |
+| `weixin_oc`               | Image, audio, video, file                 | Depends on the account connection and platform session context                                                                                                                     |
+| `weixin_official_account` | Inbound images and audio can be projected | Current send_by_session rejects proactive delivery; usable as a watch source                                                                                                       |
 
 These descriptors apply to cross-session delivery. Existing Stars' `MessageChain` sends still use adapter encoders. The planner splits content in order and enforces text and part limits. Delivery holds independent media copies; asynchronous media fetches use reusable file tokens whose copies are released on expiry. Receipts describe platform acceptance. Native quote mappings require returned message IDs; absent IDs must fall back to summaries.
 
diff --git a/docs/zh/dev/plugin-platform-adapter.md b/docs/zh/dev/plugin-platform-adapter.md
index 434b09f844..a7dbd52969 100644
--- a/docs/zh/dev/plugin-platform-adapter.md
+++ b/docs/zh/dev/plugin-platform-adapter.md
@@ -226,27 +226,27 @@ make napcat-check
 
 以下为 2026-09-11 核对本仓库 `astrbot/core/platform/sources/` 发送实现后的保守投递范围，不表示已用所有平台的真实账号联调：
 
-| 适配器目录                | 可投递媒体             | 主要限制或处理                                                                          |
-| ------------------------- | ---------------------- | --------------------------------------------------------------------------------------- |
-| `aiocqhttp`               | 图片、音频、视频、文件 | OneBot 消息段；保留图文顺序和有映射的引用                                               |
-| `napcat`                  | 图片、音频、视频、文件 | OneBot/NapCat 消息段；原生内容按种类声明                                                |
-| `telegram`                | 图片、音频、视频、文件 | 当前桥接按顺序拆发；4096 文本上限；不复用其他 Bot 的 file_id                            |
-| `discord`                 | 图片、音频、文件       | 2000 文本上限；跨会话转发禁用提及通知；视频作为普通文件投递                             |
-| `kook`                    | 图片、音频、视频、文件 | 各组件分别发送；支持引用和 JSON 卡片                                                    |
-| `lark`                    | 图片、音频、视频、文件 | 卡片及上传由飞书发送器处理；桥接引用降级为摘要                                          |
-| `line`                    | 图片、音频、视频、文件 | 每次最多 5 段，文字 5000；媒体需要可访问的 HTTPS `callback_api_base`                    |
-| `mattermost`              | 图片、音频、视频、文件 | 媒体先上传；引用使用 root_id                                                            |
-| `misskey`                 | 图片、音频、视频、文件 | 媒体取决于文件上传开关；长度取实例配置；引用摘要                                        |
-| `satori`                  | 图片、音频、视频、文件 | 能否接受具体内容仍取决于 Satori 后端及所接平台                                          |
-| `slack`                   | 图片、文件             | blocks/上传路径；桥接文字使用 plain_text；引用摘要                                      |
-| `dingtalk`                | 图片、音频、视频、文件 | 不同媒体使用不同上传和消息模板；引用摘要                                                |
-| `qqofficial`              | 图片、音频、视频、文件 | 实际类型名为 qq_official；群/频道根据缓存消息 ID 和主动发送模式判断；频道媒体保守限图片 |
-| `qqofficial_webhook`      | 图片、音频、视频、文件 | 实际类型名为 qq_official_webhook；共用官方发送逻辑及会话限制                            |
-| `webchat`                 | 图片、音频、视频、文件 | 通过 WebChat 队列投递；桥接引用摘要                                                     |
-| `wecom`                   | 图片、音频、视频、文件 | 应用模式需 agent_id；客服模式不支持主动发送                                             |
-| `wecom_ai_bot`            | 图片、音频、视频、文件 | 主动发送要求配置推送 Webhook；视频作为文件上传                                          |
-| `weixin_oc`               | 图片、音频、视频、文件 | 发送依赖当前账号连接及平台会话上下文                                                    |
-| `weixin_official_account` | 接收侧图片、音频可投影 | 当前 send_by_session 拒绝主动发送，可作为监听来源                                       |
+| 适配器目录                | 可投递媒体             | 主要限制或处理                                                                                                                          |
+| ------------------------- | ---------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
+| `aiocqhttp`               | 图片、音频、视频、文件 | OneBot 消息段；保留图文顺序和有映射的引用                                                                                               |
+| `napcat`                  | 图片、音频、视频、文件 | OneBot/NapCat 消息段；AstrBot 可读的本地/file:// 媒体编码为 `base64://`；HTTP、已有 base64 和 NapCat 侧路径原样传递；原生内容按种类声明 |
+| `telegram`                | 图片、音频、视频、文件 | 当前桥接按顺序拆发；4096 文本上限；不复用其他 Bot 的 file_id                                                                            |
+| `discord`                 | 图片、音频、文件       | 2000 文本上限；跨会话转发禁用提及通知；视频作为普通文件投递                                                                             |
+| `kook`                    | 图片、音频、视频、文件 | 各组件分别发送；支持引用和 JSON 卡片                                                                                                    |
+| `lark`                    | 图片、音频、视频、文件 | 卡片及上传由飞书发送器处理；桥接引用降级为摘要                                                                                          |
+| `line`                    | 图片、音频、视频、文件 | 每次最多 5 段，文字 5000；媒体需要可访问的 HTTPS `callback_api_base`                                                                    |
+| `mattermost`              | 图片、音频、视频、文件 | 媒体先上传；引用使用 root_id                                                                                                            |
+| `misskey`                 | 图片、音频、视频、文件 | 媒体取决于文件上传开关；长度取实例配置；引用摘要                                                                                        |
+| `satori`                  | 图片、音频、视频、文件 | 能否接受具体内容仍取决于 Satori 后端及所接平台                                                                                          |
+| `slack`                   | 图片、文件             | blocks/上传路径；桥接文字使用 plain_text；引用摘要                                                                                      |
+| `dingtalk`                | 图片、音频、视频、文件 | 不同媒体使用不同上传和消息模板；引用摘要                                                                                                |
+| `qqofficial`              | 图片、音频、视频、文件 | 实际类型名为 qq_official；群/频道根据缓存消息 ID 和主动发送模式判断；频道媒体保守限图片                                                 |
+| `qqofficial_webhook`      | 图片、音频、视频、文件 | 实际类型名为 qq_official_webhook；共用官方发送逻辑及会话限制                                                                            |
+| `webchat`                 | 图片、音频、视频、文件 | 通过 WebChat 队列投递；桥接引用摘要                                                                                                     |
+| `wecom`                   | 图片、音频、视频、文件 | 应用模式需 agent_id；客服模式不支持主动发送                                                                                             |
+| `wecom_ai_bot`            | 图片、音频、视频、文件 | 主动发送要求配置推送 Webhook；视频作为文件上传                                                                                          |
+| `weixin_oc`               | 图片、音频、视频、文件 | 发送依赖当前账号连接及平台会话上下文                                                                                                    |
+| `weixin_official_account` | 接收侧图片、音频可投影 | 当前 send_by_session 拒绝主动发送，可作为监听来源                                                                                       |
 
 这些能力只用于当前跨会话投递路径。现有 Stars 的 `MessageChain` 发送接口仍由各适配器编码。规划器按顺序拆分并执行文本/段数限制，媒体在投递期间持有独立副本，需要异步拉取的目标使用可重复读取、到期释放的文件令牌。发送回执表示平台接受情况；仅有平台返回的消息 ID 才能建立原生引用映射，缺失 ID 时必须退回摘要。
 
diff --git a/tests/unit/platform/test_napcat_outbound.py b/tests/unit/platform/test_napcat_outbound.py
index a4222b8c04..8e2257fa48 100644
--- a/tests/unit/platform/test_napcat_outbound.py
+++ b/tests/unit/platform/test_napcat_outbound.py
@@ -1,6 +1,8 @@
 from __future__ import annotations
 
+import base64
 from types import SimpleNamespace
+from unittest.mock import AsyncMock
 
 import pytest
 
@@ -45,6 +47,265 @@ async def test_napcat_outbound_builder_supports_record_video_and_file_segments()
     assert payload[2].to_dict()["data"]["name"] == "demo.txt"
 
 
+@pytest.mark.asyncio
+async def test_napcat_outbound_encodes_bridged_local_image_as_base64(tmp_path):
+    media = tmp_path / "photo.jpg"
+    image_bytes = b"\xff\xd8\xff\xd9"
+    media.write_bytes(image_bytes)
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain([Image.fromFileSystem(media)])
+    )
+
+    assert isinstance(payload, list)
+    assert len(payload) == 1
+    data = payload[0].to_dict()["data"]
+    assert data["file"] == "base64://" + base64.b64encode(image_bytes).decode()
+    assert "path" not in data
+    assert "url" not in data
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_encodes_delivery_file_uri_image_as_base64(tmp_path):
+    media = tmp_path / "0.jpg"
+    image_bytes = b"\xff\xd8\xff\xd9"
+    media.write_bytes(image_bytes)
+    uri = media.as_uri()
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain([Image(file=uri, path=uri)])
+    )
+
+    assert isinstance(payload, list)
+    data = payload[0].to_dict()["data"]
+    assert data["file"] == "base64://" + base64.b64encode(image_bytes).decode()
+    assert "path" not in data
+    assert "url" not in data
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_passes_through_http_and_base64_images():
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Image.fromURL("https://example.com/a.jpg"),
+                Image.fromBase64("dGVzdA=="),
+            ]
+        )
+    )
+
+    assert [segment.to_dict()["data"]["file"] for segment in payload] == [
+        "https://example.com/a.jpg",
+        "base64://dGVzdA==",
+    ]
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_prefers_http_url_over_cache_image_name():
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Image(
+                    file="0d2bb1468a87d64414f8e563cc61c33c.jpg",
+                    url="https://gchat.qpic.cn/demo.jpg",
+                )
+            ]
+        )
+    )
+
+    data = payload[0].to_dict()["data"]
+    assert data["file"] == "https://gchat.qpic.cn/demo.jpg"
+    assert data["url"] == "https://gchat.qpic.cn/demo.jpg"
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_passes_through_bare_napcat_cache_names():
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Image(file="0d2bb1468a87d64414f8e563cc61c33c.jpg"),
+                Record(file="0d2bb1468a87d64414f8e563cc61c33c.amr"),
+            ]
+        )
+    )
+
+    assert [segment.to_dict()["data"] for segment in payload] == [
+        {"file": "0d2bb1468a87d64414f8e563cc61c33c.jpg"},
+        {"file": "0d2bb1468a87d64414f8e563cc61c33c.amr"},
+    ]
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_passes_through_unreadable_napcat_cache_paths():
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Image(
+                    file="napcat-image.png",
+                    url="file:///C:/NapCat/cache/napcat-image.png",
+                ),
+                Record(
+                    file="napcat-record.amr",
+                    url="file:///C:/NapCat/cache/napcat-record.amr",
+                    path="C:/NapCat/cache/napcat-record.amr",
+                ),
+            ]
+        )
+    )
+
+    assert [segment.to_dict()["data"] for segment in payload] == [
+        {
+            "file": "napcat-image.png",
+            "url": "file:///C:/NapCat/cache/napcat-image.png",
+        },
+        {
+            "file": "napcat-record.amr",
+            "url": "file:///C:/NapCat/cache/napcat-record.amr",
+            "path": "C:/NapCat/cache/napcat-record.amr",
+        },
+    ]
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_passes_through_unreadable_file_uri_image():
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Plain("before"),
+                Image(file="file:///missing.jpg"),
+                Plain("after"),
+            ]
+        )
+    )
+
+    assert [segment.to_dict()["type"] for segment in payload] == [
+        "text",
+        "image",
+        "text",
+    ]
+    assert payload[1].to_dict()["data"]["file"] == "file:///missing.jpg"
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_encodes_local_record_video_and_file_as_base64(
+    tmp_path,
+):
+    record_bytes = b"#!AMR\nlocal-record"
+    video_bytes = b"\x00\x00\x00\x18ftypmp42"
+    file_bytes = b"attachment-bytes"
+    record_path = tmp_path / "voice.amr"
+    video_path = tmp_path / "clip.mp4"
+    file_path = tmp_path / "note.txt"
+    record_path.write_bytes(record_bytes)
+    video_path.write_bytes(video_bytes)
+    file_path.write_bytes(file_bytes)
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Record.fromFileSystem(record_path),
+                Video.fromFileSystem(video_path),
+                File(name="note.txt", file=str(file_path)),
+            ]
+        )
+    )
+
+    assert [segment.to_dict()["type"] for segment in payload] == [
+        "record",
+        "video",
+        "file",
+    ]
+    assert payload[0].to_dict()["data"]["file"] == (
+        "base64://" + base64.b64encode(record_bytes).decode()
+    )
+    assert payload[1].to_dict()["data"]["file"] == (
+        "base64://" + base64.b64encode(video_bytes).decode()
+    )
+    assert payload[2].to_dict()["data"]["file"] == (
+        "base64://" + base64.b64encode(file_bytes).decode()
+    )
+    assert payload[2].to_dict()["data"]["name"] == "note.txt"
+    assert "path" not in payload[0].to_dict()["data"]
+    assert "url" not in payload[1].to_dict()["data"]
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_omits_readable_local_path_when_http_url_is_used(
+    tmp_path,
+):
+    media = tmp_path / "photo.jpg"
+    media.write_bytes(b"\xff\xd8\xff\xd9")
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    payload = await adapter._build_outbound_message(
+        MessageChain(
+            [
+                Image(
+                    file="https://example.com/a.jpg",
+                    path=str(media),
+                )
+            ]
+        )
+    )
+
+    data = payload[0].to_dict()["data"]
+    assert data["file"] == "https://example.com/a.jpg"
+    assert "path" not in data
+
+
+@pytest.mark.asyncio
+async def test_napcat_outbound_skips_image_when_base64_encoding_fails(
+    monkeypatch,
+    tmp_path,
+    caplog,
+):
+    media = tmp_path / "photo.jpg"
+    media.write_bytes(b"\xff\xd8\xff\xd9")
+    monkeypatch.setattr(
+        napcat_adapter.MediaResolver,
+        "to_base64",
+        AsyncMock(side_effect=ValueError("unreadable media")),
+    )
+    queue: asyncio.Queue = asyncio.Queue()
+    adapter = _make_adapter(queue)
+    with caplog.at_level("WARNING"):
+        payload = await adapter._build_outbound_message(
+            MessageChain(
+                [
+                    Plain("before"),
+                    Image.fromFileSystem(media),
+                    Plain("after"),
+                ]
+            )
+        )
+
+    assert isinstance(payload, list)
+    assert [segment.to_dict()["type"] for segment in payload] == [
+        "text",
+        "text",
+        "text",
+    ]
+    assert payload[0].to_dict()["data"]["text"] == "before"
+    assert payload[1].to_dict()["data"]["text"] == "[Image]"
+    assert payload[2].to_dict()["data"]["text"] == "after"
+    assert any(
+        "Failed to encode outbound Image" in message for message in caplog.messages
+    )
+
+
 @pytest.mark.asyncio
 async def test_napcat_outbound_builder_supports_face_contact_location_poke_and_json():
     queue: asyncio.Queue = asyncio.Queue()